1. Field of the Invention
This invention relates to inhibitors, compositions, and processes for deoxidizing and/or cleaning surfaces of aluminum and titanium and their alloys that contain at least 45% by weight of aluminum or titanium. "Deoxidizing" is to be understood herein as the removal from the surface of metals of oxide films and other adherent inorganic materials that would reduce adhesion to subsequently applied protective coatings such as conversion coatings and/or paints and the like, and "cleaning" means removal of all other foreign materials, especially organic soils and poorly adherent inorganic substances such as metal dust and the like, that would reduce adhesion to such subsequently applied protective coatings.
2. Statement of Related Art
With most deoxidizing agents, especially acidic aqueous liquid compositions with substantial free fluoride ion activity, which are probably the most effective chemical class of cleaners and deoxidizers for aluminum and titanium now known, there is a perceptible but controlled etching or dissolution of the underlying aluminum or titanium while the deoxidizing agent is in contact with it. Such etching is often harmless or even desirable, as when it improves the smoothness of the metal surface being treated. In some instances, however, particularly where very narrow dimensional tolerances on the substrate need to be maintained, effective cleaning and deoxidizing with little or no etching is desirable, but heretofore has been very difficult to obtain.